From 81c85afbea23af449d9121365f837595a0da6f51 Mon Sep 17 00:00:00 2001
From: Celestino Amoroso <celestino.amoroso@gmail.com>
Date: Sat, 27 Apr 2024 22:32:57 +0200
Subject: [PATCH] operand-iterator.go: accepts two new optional functions
 'reset' and 'clean' from data-source

---
 operand-iterator.go | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/operand-iterator.go b/operand-iterator.go
index 5f062f6..0bad7ad 100644
--- a/operand-iterator.go
+++ b/operand-iterator.go
@@ -54,14 +54,23 @@ func getDataSourceDict(ctx ExprContext, self *term) (ds map[string]Functor, err
 
 	if dictAny, ok := value.(map[any]any); ok {
 		ds = make(map[string]Functor)
-		for _, k := range []string{initName, currentName, nextName} {
+		// required functions
+		for _, k := range []string{currentName, nextName} {
 			if item, exists := dictAny[k]; exists && item != nil {
 				if functor, ok := item.(*funcDefFunctor); ok {
 					ds[k] = functor
 				}
-			} else if k != initName {
+			} else {
 				err = fmt.Errorf("the data-source must provide a non-nil %q operator", k)
-				break
+				return
+			}
+		}
+		// Optional functions
+		for _, k := range []string{initName, resetName, cleanName} {
+			if item, exists := dictAny[k]; exists && item != nil {
+				if functor, ok := item.(*funcDefFunctor); ok {
+					ds[k] = functor
+				}
 			}
 		}
 	} else {
@@ -98,6 +107,9 @@ func evalIterator(ctx ExprContext, self *term) (v any, err error) {
 
 	dc.nextFunc, _ = ds[nextName]
 	dc.currentFunc, _ = ds[currentName]
+	dc.cleanFunc, _ = ds[cleanName]
+	dc.resetFunc, _ = ds[resetName]
+
 	v = dc
 
 	return